Spelunky

Spelunky is a cave exploration / treasure-hunting game inspired by classic platform games and #roguelikes, where the goal is to grab as much treasure from the cave as possible. Every time you play the cave's layout will be different. Use your wits, your reflexes, and the items available to you to survive and go ever deeper!

Don't be afraid to die! But also don't be afraid to live! Happy Spelunky-ing!

This is the original freeware version of Spelunky that was released in 2009 and started it all. It's still free, so check it out! However, if you're looking for the HD reboot that was released in 2012, you can find that here: http://spelunkyworld.com/buy.html